[Qemu-devel] [PATCH 18/24] block: Initial implementation of -blockdev

Markus Armbruster posted 24 patches 8 years, 11 months ago
There is a newer version of this series
[Qemu-devel] [PATCH 18/24] block: Initial implementation of -blockdev
Posted by Markus Armbruster 8 years, 11 months ago
The new command line option -blockdev works like QMP command
blockdev-add.

The option argument may be given in JSON syntax, exactly as in QMP.
Example usage:

    -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": "file", "filename": "foo.img"} }'

The JSON argument doesn't exactly blend into the existing option
syntax, so the traditional KEY=VALUE,... syntax is also supported,
using dotted keys to do the nesting:

    -blockdev node-name=foo,driver=raw,file.driver=file,file.filename=foo.img

This does not yet support lists or downstream extensions, i.e. keys
with __RFQDN_ prefix, but the next few patches will take care of that.

Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
right away would crash.  We need to stash the configuration for later
instead.  This is crudely done, and bypasses QemuOpts, even though
storing configuration is what QemuOpts is for.  Need to revamp option
infrastructure to support QAPI types like BlockdevOptions.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 qemu-options.hx |  7 +++++++
 vl.c            | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/qemu-options.hx b/qemu-options.hx
index bf458f8..8f02264 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -532,6 +532,13 @@ Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
 using @file{/dev/cdrom} as filename (@pxref{host_drives}).
 ETEXI
 
+DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
+    "-blockdev driver[,node-name=N][,discard=ignore|unmap]\n"
+    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
+    "          [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
+    "          [,driver specific parameters...]\n"
+    "                configure a block backend\n", QEMU_ARCH_ALL)
+
 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
     "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
diff --git a/vl.c b/vl.c
index c6020b9..0684d52 100644
--- a/vl.c
+++ b/vl.c
@@ -95,6 +95,9 @@ int main(int argc, char **argv)
 #include "migration/colo.h"
 #include "sysemu/kvm.h"
 #include "sysemu/hax.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi-visit.h"
 #include "qapi/qmp/qjson.h"
 #include "qemu/option.h"
 #include "qemu/config-file.h"
@@ -2975,6 +2978,13 @@ int main(int argc, char **argv, char **envp)
     Error *main_loop_err = NULL;
     Error *err = NULL;
     bool list_data_dirs = false;
+    typedef struct BlockdevOptions_queue {
+        BlockdevOptions *bdo;
+        Location loc;
+        QSIMPLEQ_ENTRY(BlockdevOptions_queue) entry;
+    } BlockdevOptions_queue;
+    QSIMPLEQ_HEAD(, BlockdevOptions_queue) bdo_queue
+        = QSIMPLEQ_HEAD_INITIALIZER(bdo_queue);
 
     module_call_init(MODULE_INIT_TRACE);
 
@@ -3117,6 +3127,25 @@ int main(int argc, char **argv, char **envp)
                 drive_add(IF_DEFAULT, popt->index - QEMU_OPTION_hda, optarg,
                           HD_OPTS);
                 break;
+            case QEMU_OPTION_blockdev:
+                {
+                    Visitor *v;
+                    BlockdevOptions_queue *bdo;
+
+                    v = qobject_input_visitor_new_str(optarg, "driver", &err);
+                    if (!v) {
+                        error_report_err(err);
+                        exit(1);
+                    }
+
+                    bdo = g_new(BlockdevOptions_queue, 1);
+                    visit_type_BlockdevOptions(v, NULL, &bdo->bdo,
+                                               &error_fatal);
+                    visit_free(v);
+                    loc_save(&bdo->loc);
+                    QSIMPLEQ_INSERT_TAIL(&bdo_queue, bdo, entry);
+                    break;
+                }
             case QEMU_OPTION_drive:
                 if (drive_def(optarg) == NULL) {
                     exit(1);
@@ -4454,6 +4483,16 @@ int main(int argc, char **argv, char **envp)
         qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot,
                           NULL, NULL);
     }
+    while (!QSIMPLEQ_EMPTY(&bdo_queue)) {
+        BlockdevOptions_queue *bdo = QSIMPLEQ_FIRST(&bdo_queue);
+
+        QSIMPLEQ_REMOVE_HEAD(&bdo_queue, entry);
+        loc_push_restore(&bdo->loc);
+        qmp_blockdev_add(bdo->bdo, &error_fatal);
+        loc_pop(&bdo->loc);
+        qapi_free_BlockdevOptions(bdo->bdo);
+        g_free(bdo);
+    }
     if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func,
                           &machine_class->block_default_type, NULL)) {
         exit(1);
-- 
2.7.4


Re: [Qemu-devel] [PATCH 18/24] block: Initial implementation of -blockdev
Posted by Eric Blake 8 years, 11 months ago
On 02/27/2017 05:20 AM, Markus Armbruster wrote:
> The new command line option -blockdev works like QMP command
> blockdev-add.
> 
> The option argument may be given in JSON syntax, exactly as in QMP.
> Example usage:
> 
>     -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": "file", "filename": "foo.img"} }'
> 
> The JSON argument doesn't exactly blend into the existing option
> syntax, so the traditional KEY=VALUE,... syntax is also supported,
> using dotted keys to do the nesting:
> 
>     -blockdev node-name=foo,driver=raw,file.driver=file,file.filename=foo.img
> 
> This does not yet support lists or downstream extensions, i.e. keys
> with __RFQDN_ prefix, but the next few patches will take care of that.
> 
> Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
> right away would crash.  We need to stash the configuration for later
> instead.  This is crudely done, and bypasses QemuOpts, even though
> storing configuration is what QemuOpts is for.  Need to revamp option
> infrastructure to support QAPI types like BlockdevOptions.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  qemu-options.hx |  7 +++++++
>  vl.c            | 39 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/qemu-options.hx b/qemu-options.hx
> index bf458f8..8f02264 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -532,6 +532,13 @@ Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
>  using @file{/dev/cdrom} as filename (@pxref{host_drives}).
>  ETEXI
>  
> +DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
> +    "-blockdev driver[,node-name=N][,discard=ignore|unmap]\n"

Maybe "-blockdev [driver=]DRIVER[,node-name".....

to call out that you use driver as an implied key? But I'm also fine
with what you wrote (it's sufficient enough for a human reading it, and
the help output is not scraped by libvirt).

> +    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
> +    "          [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
> +    "          [,driver specific parameters...]\n"
> +    "                configure a block backend\n", QEMU_ARCH_ALL)
> +
>  DEF("drive", HAS_ARG, QEMU_OPTION_drive,
>      "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
>      "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

Re: [Qemu-devel] [PATCH 18/24] block: Initial implementation of -blockdev
Posted by Kevin Wolf 8 years, 11 months ago
Am 27.02.2017 um 12:20 hat Markus Armbruster geschrieben:
> The new command line option -blockdev works like QMP command
> blockdev-add.
> 
> The option argument may be given in JSON syntax, exactly as in QMP.
> Example usage:
> 
>     -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": "file", "filename": "foo.img"} }'
> 
> The JSON argument doesn't exactly blend into the existing option
> syntax, so the traditional KEY=VALUE,... syntax is also supported,
> using dotted keys to do the nesting:
> 
>     -blockdev node-name=foo,driver=raw,file.driver=file,file.filename=foo.img
> 
> This does not yet support lists or downstream extensions, i.e. keys
> with __RFQDN_ prefix, but the next few patches will take care of that.
> 
> Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
> right away would crash.  We need to stash the configuration for later
> instead.  This is crudely done, and bypasses QemuOpts, even though
> storing configuration is what QemuOpts is for.  Need to revamp option
> infrastructure to support QAPI types like BlockdevOptions.
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>

Apparently I forgot to actually reply here after going back to the
previous patch...

> @@ -532,6 +532,13 @@ Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
>  using @file{/dev/cdrom} as filename (@pxref{host_drives}).
>  ETEXI
>  
> +DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
> +    "-blockdev driver[,node-name=N][,discard=ignore|unmap]\n"

I was going to suggest the same thing as Eric here, simply 'driver'
doesn't look right.

> +    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
> +    "          [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
> +    "          [,driver specific parameters...]\n"
> +    "                configure a block backend\n", QEMU_ARCH_ALL)
> +
>  DEF("drive", HAS_ARG, QEMU_OPTION_drive,
>      "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
>      "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"

> @@ -4454,6 +4483,16 @@ int main(int argc, char **argv, char **envp)
>          qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot,
>                            NULL, NULL);
>      }
> +    while (!QSIMPLEQ_EMPTY(&bdo_queue)) {
> +        BlockdevOptions_queue *bdo = QSIMPLEQ_FIRST(&bdo_queue);
> +
> +        QSIMPLEQ_REMOVE_HEAD(&bdo_queue, entry);
> +        loc_push_restore(&bdo->loc);
> +        qmp_blockdev_add(bdo->bdo, &error_fatal);
> +        loc_pop(&bdo->loc);
> +        qapi_free_BlockdevOptions(bdo->bdo);
> +        g_free(bdo);
> +    }
>      if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func,
>                            &machine_class->block_default_type, NULL)) {
>          exit(1);

And here I found the placement of the new code odd, it's in the middle
of -drive handling. The current placement means that -drive can
reference -blockdev nodes, but not the other way round. I like this and
wouldn't recommand changing it. So my suggestion for a better placement
would be to move the -blockdev code up a bit.

Kevin